AbstractWe describe the enantioselective epoxidation of straight‐chain aliphatic alkenes using a biocatalytic system containing styrene monooxygenase from Rhodococcus sp. ST‐10 and alcohol dehydrogenase from Leifsonia sp. S749. The biocatalyzed enantiomeric epoxidation of 1‐hexene to (S)‐1,2‐epoxyhexane (>44.6 mM) using 2‐propanol as the hydrogen donor was achieved under optimized conditions. The biocatalyst had broad substrate specificity for various aliphatic alkenes, including terminal, internal, unfunctionalized, and di‐ and tri‐substituted alkenes. Here, we demonstrate that this biocatalytic system is suitable for the efficient production of enantioenriched (S)‐epoxyalkanes.magnified image
Synthesis of a Benzolactone Collection using Click Chemistry
作者:Jan Ritschel、Florenz Sasse、Martin E. Maier
DOI:10.1002/ejoc.200600681
日期:2007.1
A collection of benzotriazoles consisting of seven compounds was prepared from the propynyl-substituted benzolactone 1 and various azides usingclickchemistry. The lactone 1 was obtained through a short route by direct esterification of the allylbenzoic acid 9 with the alkynol 7 giving the benzoate 2. The homopropargyl alcohol 7 in turn was obtained by opening the epoxide 6 with triisopropylsilyl
Stereoselective Syntheses of Epothilones A and B via Nitrile Oxide Cycloadditions and Related Studies
作者:Jeffrey W. Bode、Erick M. Carreira
DOI:10.1021/jo015791h
日期:2001.9.1
epothilones A and B are described. The routes described make extensive study of nitrileoxide cycloadditions as surrogates for aldoladdition reactions and have led to the realization of a highly convergent synthesis based on the Kanemasa hydroxyl-directed nitrileoxide cycloaddition. As well, our synthetic efforts have led to the development of new reaction methodologies and served as the proving ground for
Structure-Guided Regulation in the Enantioselectivity of an Epoxide Hydrolase to Produce Enantiomeric Monosubstituted Epoxides and Vicinal Diols via Kinetic Resolution
Structure-guided microtuning of an Aspergillus usamii epoxide hydrolase was executed. One mutant, A214C/A250I, displayed a 12.6-fold enhanced enantiomeric ratio (E = 202) toward rac-styrene oxide, achieving its nearly perfect kinetic resolution at 0.8 M in pure water or 1.6 M in n-hexanol/water. Several other beneficial mutants also displayed significantly improved E values, offering promising biocatalysts
对Aspergillus usamii环氧水解酶进行了结构引导的微调。一种突变体 A214C/A250I对消旋-氧化苯乙烯的对映体比 ( E = 202)提高了 12.6 倍,在纯水中 0.8 M 或正己醇/水中 1.6 M 时实现了近乎完美的动力学分辨率。其他一些有益的突变体也显示出显着提高的E值,为获得 19 种结构多样的手性单取代环氧化物(97.1 – ≥ 99% ee s)和邻二醇(56.2–98.0% ee p)提供了有希望的生物催化剂,并且产率很高。
Single Enantiomer Epoxides by Bromomandelation of Prochiral Alkenes
作者:Douglass F. Taber、Jiang-lin Liang
DOI:10.1021/jo061818r
日期:2007.1.1
A combination of mandelic acid and N-bromosuccinimide efficiently converts prochiral alkenes into a readily separable 1:1 mixture of the bromomandelates. The diastereomerically pure bromomandelates are then converted into a variety of enantiomerically pure products. Terminal alkenes are converted into enantiomerically pure epoxides. Cyclohexene is converted into enantiomerically pure cis-2-azidocyclohexanol and cis-2-phenylthiocyclohexanol.
“Cassette” In Situ Enzymatic Screening Identifies Complementary Chiral Scaffolds for Hydrolytic Kinetic Resolution Across a Range of Epoxides
作者:Sangeeta Dey、Douglas R. Powell、Chunhua Hu、David B. Berkowitz
DOI:10.1002/anie.200701280
日期:2007.9.17
‘Cassette’-ISES (In Situ Enzymatic Screening) Identifies Complementary Chiral Scaffolds for Hydrolytic Kinetic Resolution Across a Range of Epoxides A new ‘Cassette’-In Situ Enzymatic Screen (ISES) for combinatorial catalysis is introduced. This allows the experimentalist to obtain an information-rich readout, in real time, providing an estimate of the sense and magnitude of enantioselectivity across more than one substrate. In its first iteration, the screen identified CoIII-salen catalysts with β-pinene- and α-naphthylalanine-derived chiral scaffolds with broad, yet complementary, substrate specificities.